Syringe cartridge



March 12, 1929. R, REHM v 1,704,924

SYR I NGE CARTRIDGE Filed sept.. 5, 192s Patented Mar. 12, 1929.

UNITE-D STATES PATENT OFFICE.

ROLAND C, REHM', 0F EVANSTON, ILLINOIS, ASSIGNOR TO COOK LABORATORIES,INC.,

I A CORPORATION 0F DELAWARE.

SYRINGE CARTRIDGE.

Application led September 5, 1925. Serial No. 54,644.

This invention relates to cartridges or medicament-dispensing packagesfor use as operative components of hypodermlc s inges. The object is toprovide a cartri ge with an improved piston plug adapted upon release ofthe applied operating pressure to eXert an action counter to that whichwould tend to produce back-suction.

A cartridge embodying the invention 1n lo one practicable form is shownfor illustration in the annexed drawings, in which:

Fig. 1 is a longitudinal section of a syringe containing said cartridgeas an opera tive component thereof;

Fig. 2 is an enlarged view in longitudinal section of a fragment of thecartridge, showing the piston plug being forced forward by the syringelunger; Fig. 3 is a etailed perspective view of 20 the plston plug on anenlarged scale.

The illustrative cartridge, comprising a glass tube 12 sealed by rubberplugs or stoppers 13 and 14, is shown in Fig. 1 in an instrument whichin conjunction with the cartridge provides an operative syringe orinjection-administering organization. Said instrument comprises acartridge-holder 5 having removable heads 6 and 7. In the breech head 7is a slidable plunger rod- 8 having an enlarged inner end 9 adapted toenter the glass cartridge tube and drive the stopper 14 forward forejecting the liquid contents of the cartridge through the in'ectingneedle attached to the fore end o the instrument. Communication betweenthe cartridge and needle is established in this instance by penetrationof the inwardly projecting end of the needle throughthe readilypierccable recessed rubber'stopper`13 in the fore cnd of the cartridge.By means of an intermediate needle enlargement 11, seated in the head(i, the needle is held in place. It will be understood that thisparticular organization is merely exemplary.

The rubber plug 14, which in this instance is a slidable piston plug aswell as a sealing closure, is designed or constructed so that anydistortion which the plug undergoes by plunger thrust during thefluid-ejecting operation will not cause a back-suction bywreflexing ofthe plug when the pressure on the hw cannot cause relative forward 2:1

syringe plunger is relaxed. In fact, upon vrelease of the appliedpressure the plug will react in a manner to counteract or preventsucking-back tendency. As shown, the saidl plug 14 has an interiorclosed cavity 15 and a relativel thin front Wfall 16 exposed to theliquid in t e cartridge. The back wall of the hollow plug and itsannular wall around the cavity are relatively thick to provide asufliciently firm plug to be compressed in the cartridge tube and whichmay be pushed forward by the plungerapplied against the back end of theplug. By reason of the cavity 15, it will be apparent that the thrust ofthe plunger against the tight fitted rubber rotrusion of the majorAcentral portion o the front of the plug. Hence the opportunity fordistortion by plunger thrust in a manner which would cause back-suctionby reflexing,` is minimized. Moreover, in the fluidejecting operation,the fluid pressure in the cartridge acting against the resilient orflexible fore wall 16 will cause said wall to flex backward or bulgeinto the cavity, as indicated in Fig. 2; and when the applied pressureis released the reflexing of the wall in resuming its normal undistendedposition will be in a direction tending to continue the ejection' andthus have an effect contrary to a sucking-back tendency. IThe wall 16may be sufficiently thin to be quite flexible and to lprovide a pressuresensitive diaphragm which will be distended as soon as any pressure' isapplied on the liquid and will relax immediately after the pressureceases.

While the described piston plug may be made in various ways, Icontemplate making it by uniting two separate recessed or cupshapedsections as shown, their contacting ends being cemented or otherwisesuitably joined. Preferably the front section is ofC originally smallerdiameter than the other, 95 so that the compression of the plug wheninserted in the cartridge tube will not bow or improperly affect thcwall 1G, and also because it is deemed preferable to have the rearplllugereugageable section in tighter 1m engagement with the glass tubethan the fore section.

The described piston plug may be considered as oneembodying an elasticclosed hollow body adapted to be compressed in the tluid-ejcctingoperation, as manifested by contraction oi" the cavity, and which uponrelease of the pressure will expand toward the discharge end otl thecartridge.

In view of a prior invention of Harvey S. Cook, described and claimed inhis pending application Serial No. 71,319, filed November 25, 1925 as adivision ot' an earlier application, which vembraces a cartridge havinga rubber piston plug formed or conlstructed so that when the pressure isreleased the plug or a portion thereof exposed to the internal fluidpressure will reflex in a direction to counteract or prevent asucking-back tendency, I make no claim herein such as tov cover saidprior Cook invention.

Notice is also given that the particular syringe organization andcartridge therefor herein shown embody other vprior inventions ot saidHarvey S. Cook, including a cartridge having the kind of pierceable foreplug or stopper herein shown, and an organization comprisingr such acartridge with an instrument of substantially the construction hereinshown; which prior Cook inventions are described and claimed by him inprior applications for patent now pending.

What I claim is:

1. A medicament dispensing package comprising, in combination, a tubularbody; a plug scaling one end; and a second resilient plug initiallydisposed at the other end of the tubular body and slidable therethroughto eject the medicament through a canula which penetrates the firstnamed plug; said second plug having spaced end walls the fore one ofwhich is adapted to be deformed in the region of its axis by thehydrostatic pressure created within the package by said ejection.

2. A medicament dispensing package comprising, in combination, a tubularbody; a plug sealing one end; and a second resilient plug initiallydisposed atthe other end of the tubular body and Slidablc therethroughto eject the medicament through a canula which penetrates the firstnamed plug; said second plug having a closed hollcw interior and arelatively thin fore wall. which fleXes towards Asaid interior under thehydrostatic pressure created Within the package during the ejection.

3. A medicament dispensing package comprising, in combination, a tubularbody; and a resilient hollow7 plug sealing an opening in the body andslidablc therethrough to contract the interior volume of the package;said plug having end walls of 4diftereut thicknesses, the thinner endWall being exposed to the medicament and so made as lo be reidily liexcdby the hydrostatic pressure created during an injection, andautomatically resuming its natural unfleXed state when said pressure'isrelieved.

4. A medicament dispensing package comprising, in combination, a body;and a slidable plug for said body having a closed hollow` interior andconstructed and arranged to transmit mechanical pressure at and near theperiphery thereof and having one end face sufficiently flexible to bedistended within said hollow interior by hydrostatic pressure within thepackage.

5. A hypodermic syringe embodying a cartridge and needle incommunication therewith, said cartridge having a piston plug with aclosed hollow interior, the fore wall of which plug is adapted to beflexed by hydrostatic pressure in the fluid-ejecting operation, for thepurpose described.

6. A syringe cartridge embodying a piston plug with a closed hollowinterior, the fore wall ol which plug is adapted to be flexed byhydrostatic pressure in the Huidejecting operation, for the purposevdescribed.

7. A syringe cartridge embodying a closed hollow piston plug ofresilient material having a relatively thick back wall and a relativelythin fore wall.

8. A syringe cartridge having a piston plug composed of two sections,including a recessed or substantially cup-shaped section the recess oitwhich is closed by the other section, the loro wall of said plug adaptedto be flexed by hydrostatic pressure in the {luid-ejecting operation,for the purpose described.

9. A syringe cartridge having a piston plug comprising a rear section tobe engaged by a plunger and a substantially cupshaped fore section ofresilient material arranged with its recess facing the rear section.

10. A syringe cartridge embodying a composite plug composed ot tworecessed sections so positioned that the recesses thereof provide aclosed hollow chamber the inner one ot said sections having an en walladapted to be flexed by lhydrostatic pressure in the tluid-ejectingoperation.

11. A syringe cartridge embodying a resilient plug composed of tworecessed sections united so that the recesses provide a closed hollowchamber within the plug, one of said sections being of larger externaldiameter than the other, the smaller section having a relatively thinend wall adjacent said hollow chamber.

12. A syringe cartridge having a piston plug embodying an elastic closedhollow body adapted to be compressed in the fluidejecting operation andto expand toward the discharge end of the cartridge when the pressure isreleased, for the purpose set forth.

13. A syringe cartridge embodying a piston plug comprising an elasticstopper having a closed hollow interior, said stopper constructed toreceive and transmit plunger thrust applied against its back end andadapted to undergo compression in the fluidejectns; operation in amanner such that; when the pressure is released the stopper will exertan expansion action toward the discharge end of the cartridge, for thepur- ROLAND C. REHM.

I have signed my

